The effects of medium supplementation with oestrous goat serum and glycoprotein hormones on caprine oocyte maturation in vitro (IVM) were evidenced by proportions of resulting ova completing in vitro fertilisation (IVF) and development to the morula stage. Oocyte-cumulus complexes (OCCs) were harvested in follicular fluid from 2-5 mm diameter follicles. Oocyte maturation took place during 27 h in TCM-199 supplemented with 20% oestrous goat serum, oestradiol-17 beta (1.0 microgram/ml), and either (a) 0.5 microgram FSH/ml, (b) 100 micrograms LH/ml, (c) 100 micrograms LH + 0.5 microgram FSH/ml, (d) 100 micrograms hCG + 0.5 microgram FSH/ml, (e) 0.5 microgram TSH/ml or (f) no added glycoprotein hormone (control). Of 353 immature oocytes cultured in seven experiments, 311 (88.1%) exhibited cumulus expansion at the end of the IVM interval; all normal-appearing OCCs were inseminated. In vitro insemination was with ejaculated sperm treated with heparin (10 micrograms/ml) and caffeine (0.4 microgram/ml). Proportions (%) of inseminated ova that were fertilised (cleaved) and that reached the morula stage after IVM with (a) FSH, (b) LH, (c) LH+FSH, (d) hCG + FSH, (e) TSH and (f) no added glycoprotein hormone were (a) 22/52 (42.3%) and 9/52 (17.3%), (b) 25/54 (46.3%) and 14/54 (25.9%), (c) 52/65 (80.0%) and 26/65 (40.0%), (d) 48/78 (61.5%) and 22/78 (28.2%), (e) 14/54 (25.9%) and 4/54 (7.4%), and (f) 11/50 (22.0%) and 1/50 (2.0%), respectively. All treatments yielded better results than IVM with no added glycoprotein hormone. After IVM with added LH+FSH higher proportions of oocytes were fertilised (p < 0.05), and higher proportions reached the morula stage (p < 0.05) when compared with other treatments.