Fruit yield of cantaloup (Cucumis melol.cv. PSF 189) was not affected by the application of clear (C) or (B) plastic mulches, in comparison to unmulched soil (U), when grown inside an unheated greenhouse located in the Mediterranean mountains in a region with a cold early spring. Marketable yields of 30.5, 28.06 and 25.03 t/ha were achieved under the C, B and U treatments, respectively, during 1990. These yields were not significantly different (P>0.05). The mulches enhanced vegetative growth during the cold early spring; fully expanded leaves were 2.5 times more under C mulch, and 1.8 times more under the B mulch, than under the U treatment, by the fifth week after planting. Fruiting occurred later on when the weather warmed and thus no significant effect on yield occurred due to the mulches. Soil temperature at 10 cm depth under the C treatment was warmer by 1–2°C and 7–10°C than temperature under the B and U treatments respectively, when the plant canopy did not cover the mulches but became comparable among the mulches when they became covered by the plant canopy.