New 1-adamanyl-1,3,4-thiadiazole derivatives namely, 5-(1-adamantyl)-1,3,4-thiadiazoline-2-thione 3, 5-(1-adamantyl)-3-(benzyl- or 4-substituted benzyl)-1,3,4-thiadiazoline-2-thione 4a-d, 5-(1-adamantyl)-3-(4-substituted-1-piperazinylmethyl)-1,3,4-thiadiazoline-2-thiones 5a-c, 2-[5-(1-adamantyl)-2-thioxo-1,3,4-thiadiazolin-3-yl]acetic acid 7, (±)-2-[5-(1-adamantyl)-2-thioxo-1,3,4-thiadiazolin-3-yl]propionic acid 9, 3-[5-(1-adamantyl)-2-thioxo-1,3,4-thiadiazolin-3-yl]propionic acid 11, N-[5-(1-adamantyl)-1,3,4-thiadiazol-2-yl]-N'-arylthioureas 15a-c and 5-(1-adamantyl)-1,3,4-thiadiazoline-2-one 16, were synthesized and tested for in vitro activities against a panel of gram-positive and gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Compounds 7, 9, 15b and 15c displayed marked activity against the tested gram-positive bacteria, while compound 3 was highly active against the tested gram-negative bacteria. Compounds 4b, 7 and 15c were weakly or moderately active against C. albicans. In addition, the in vivo anti-inflammatory activity of the synthesized compounds was determined using the carrageenan-induced paw oedema method in rats. The propionic acid derivative 9 produced good dose-dependent anti-inflammatory activity.