Damping-off disease affects most greenhouse cucumber crops in Oman with losses frequently exceeding 25% of seedlings. Different local and introduced rootstocks were assessed for their response to Pythium aphanidermatum infection. Rootstocks were tested for grafting compatibility and production potential under greenhouse conditions. During in vivo infection tests, no infection was observed in C. moschata × C. maxima varieties Hercules and Titan, Indian ridge gourd and Omani sponge gourd. In greenhouse tests, Titan and Hercules hybrids and squash var. Magda showed no infection up to 45 days after transplanting. Magda (58%) and Hercules (80%) and Titan (84%) had highest compatibilities with cucumber variety Zena. Titan and Hercules rootstocks significantly increased vegetative growth of Zena cucumber. Titan and Hercules rootstocks significantly increased fruit number and weight compared to the control. However, Zena grafted on Zena and Salalah cucumber produced significantly less yield compared to the non-grafted Zena control. Titan and Hercules, Salalah cucumber, Magda squash, Omani sponge gourd and Indian ridge gourd rootstocks significantly increased fruit length, and improved fruit diameter and total soluble solid (TSS). No damping off infection was observed on Titan and Hercules rootstocks during either greenhouse season.