Hyper dynamic business environment has rendered the pursuit of sustained competitive advantage untenable, hence the need to focus on transient competitive advantage which is a combination of various factors, which result in the ability of the firm to adapt swiftly to a fast-changing environment. This study’s’ purpose was to assess the influence of strategic aggressiveness posture on adoption of transient competitive advantage. The precise objective of the study entailed was to assess the influence of strategic aggressiveness posture on the adoption of transient competitive advantage by private multi-practice hospitals in Nairobi City County, Kenya. This study was guided by the dynamic capability theory of the firm and McGrath transient competitive advantage theory. The study adopted a descriptive correlational survey research design. The total target population was 400 hospital administrators from which a sample size of 200 respondents was selected using Stratified random sampling method. To enhance reliability and validity of study instruments, a pilot study was carried out whereby a reliability coefficient of 0.7 was considered acceptable. Both descriptive and inferential data analysis methods were used to analyze data. Analysis of data was done within acceptance margin of error of 0.95. Regression beta coefficients were used to examine influence of the independent variables on the dependent variable among private multi-practice hospitals in Nairobi city County in Kenya. The study found out that that strategic aggressiveness posture had a statistically significant influence on transient competitive advantage (β= 0.397(t=.000) and with model prediction of R square 0.292 significant at F=.000). The study concludes that strategic aggressiveness posture has a statistically significant influence on transient competitive advantage among private multi-practice hospitals in Nairobi city County in Kenya. Thus the study recommends the hospitals’ policy reviews to capture these areas for improvement: review policy to revamp competition analysis, increase market assertiveness and soldier towards best cost provision as well as adopt unpredictability in services differentiation.