The objective of the present study was to establish the total weight (W)-carapace length (CL) relationship and condition factor (Cf) of the spiny lobster Panulirus penicillatus (Olivier, 1791) in the Sudanese Red Sea coast. Sixty specimens were used in the study. The male: female ratio was 1: 1.63. The minimum, maximum, and mean CL of male, female, and mixed male/female lobsters were (4.5-13.7, 8.34 cm), (4.2-12.3, 7.95 cm) and (4.2-13.7, 8.1 cm) consecutively. The corresponding W were (136-995, 488 gm), (170-1243, 456 gm) and (136-1243, 468.17 gm). The "b" values of the power regression of W vs. CL were 2.118, 2.281, and 2.208 for male, female, and mixed male/female lobsters in order, indicating negative allometric growth. Cf based on W and CL was 0.0837, 0.0865 and 0.0854 for male, female, and mixed male/female lobsters. The regression of Cf vs CL indicated that Cf decreased during growth. The study concluded that Sudan Red Sea coast water is conducive for lobster growth.