Cultivation of parthenocarpic cucumber in greenhouses having partial environment control has been undertaken during last decade in our country and very little work has been done for developing varieties and hybrids for protected environment. Thus, there is a need to identify cultivars suitable for protected cultivation in different seasons and regions of the country. The present investigation entitled, "Genetic evaluation of some hybrids of cucumber under modified naturally ventilated greenhouse in mid hills of Western Himalayas" was undertaken to assess the nature and magnitude of genetic variability, association among various traits and marketable yield and their direct and indirect effects during spring summer and autumn winter, 2011. On the basis of mean performance, some parthenocarpic cucumber hybrids were identified for commercial cultivation in modified naturally ventilated polyhouses in mid hills of Western Himalayas. As a result of this study, some of these hybrids wereaccepted by the farmers of local areas and are being cultivated successfully in various types of protected structures.