| The Vampire and the Ballerina | 1960 | Screenplay |
| Che femmina!! E... che dollari! | 1960 | Screenplay |
| Rocco e le sorelle | 1961 | Screenplay |
| Werewolf in a Girls' Dormitory | 1961 | Writer |
| Pesci d'oro e bikini d'argento | 1961 | Screenplay |
| Last Chance for Life | 1962 | Writer |
| The Horrible Dr. Hichcock | 1962 | Writer |
| Alone Against Rome | 1962 | Screenplay |
| Son of Hercules vs. Medusa | 1963 | Screenplay |
| Divorzio alla siciliana | 1963 | Screenplay |
| Horror Castle | 1963 | Screenplay |
| The Whip and the Body | 1963 | Screenplay |
| Hercules and the Masked Rider | 1963 | Writer |
| Scandal Nudes | 1963 | Screenplay |
| Crypt of the Vampire | 1964 | Screenplay |
| The Monster of the Opera | 1964 | Screenplay |
| Giants of Rome | 1964 | Screenplay |
| The Revenge of the Gladiators | 1964 | Writer |
| Secret Agent Fireball | 1965 | Screenplay |
| Libido | 1965 | Producer |
| Libido | 1965 | Screenplay |
| Special Code: Assignment Lost Formula | 1966 | Writer |
| Killers Are Challenged | 1966 | Screenplay |
| The Murder Clinic | 1966 | Screenplay |
| Fury in Marrakesh | 1966 | Writer |
| Almost Perfect Crime | 1966 | Screenplay |
| Where Are You Taking That Woman | 1966 | Screenplay |
| Arizona Colt | 1966 | Screenplay |
| Ring Around the World | 1966 | Screenplay |
| $1,000 on the Black | 1966 | Writer |
| Your Turn to Die | 1967 | Screenplay |
| $10,000 for a Massacre | 1967 | Screenplay |
| Flashman | 1967 | Writer |
| Vengeance Is Mine | 1967 | Screenplay |
| Day of Anger | 1967 | Screenplay |
| The Sweet Body of Deborah | 1968 | Writer |
| Taste of Vengeance | 1968 | Screenplay |
| Cheers... Cyanide! | 1968 | Screenplay |
| To Hell and Back | 1968 | Screenplay |
| Diamonds for Breakfast | 1968 | Writer |
| The Battle of El Alamein | 1969 | Screenplay |
| Desert Assault | 1969 | Writer |
| So Sweet... So Perverse | 1969 | Screenplay |
| The Forbidden Photos of a Lady Above Suspicion | 1970 | Screenplay |
| Light the Fuse… Sartana Is Coming | 1970 | Screenplay |
| The Strange Vice of Mrs Wardh | 1971 | Screenplay |
| The Lonely Violent Beach | 1971 | Writer |
| Human Cobras | 1971 | Screenplay |
| The Case of the Scorpion's Tail | 1971 | Screenplay |
| Death Walks on High Heels | 1971 | Screenplay |
| All the Colours of the Dark | 1972 | Screenplay |
| Prey of Vultures | 1972 | Screenplay |
| The Case of the Bloody Iris | 1972 | Screenplay |
| Your Vice Is a Locked Room and Only I Have the Key | 1972 | Screenplay |
| Death Walks at Midnight | 1972 | Screenplay |
| A Reason to Live, a Reason to Die | 1972 | Screenplay |
| The Grand Duel | 1972 | Screenplay |
| Torso | 1973 | Screenplay |
| The Violent Professionals | 1973 | Screenplay |
| Anna: the Pleasure, the Torment | 1973 | Screenplay |
| My Name Is Nobody | 1973 | Screenplay |
| Almost Human | 1974 | Screenplay |
| Puzzle | 1974 | Screenplay |
| Gun Moll | 1975 | Writer |
| Gambling City | 1975 | Screenplay |
| The Suspicious Death of a Minor | 1975 | Screenplay |
| Kidnap Syndicate | 1975 | Screenplay |
| Savage Three | 1975 | Screenplay |
| A Genius, Two Friends, and an Idiot | 1975 | Screenplay |
| The Cynic, the Rat & the Fist | 1977 | Screenplay |
| Sahara Cross | 1977 | Screenplay |
| Concorde Affair | 1979 | Screenplay |
| The Great Alligator | 1979 | Writer |
| I'm Getting a Yacht | 1980 | Screenplay |
| Screams in the Night | 1981 | Writer |
| Lo Scorpione a Due Code | 1982 | Writer |
| Scorpion with Two Tails | 1982 | Screenplay |
| 2019: After the Fall of New York | 1983 | Screenplay |
| The Killer Is Still Among Us | 1986 | Screenplay |
| Provare per credere | 1987 | Writer |
| The Shatterer | 1987 | Screenplay |
| Stradivari | 1988 | Screenplay |
| Jiboa | 1989 | Writer |
| Casablanca Express | 1989 | Screenplay |
| Il giorno del giudizio | 1994 | Writer |
