Four Neandertal fossils yielded only Neandertal-specific mtDNA sequences. Five early modern human fossils contained no Neandertal mtDNA despite similar preservation. Neandertal-like mtDNA found in all well-preserved Neandertal remains. Modern human contamination ubiquitous in ancient samples but Neandertal mtDNA authentic. Transitional fossils Vindija and Mladeč lack Neandertal mtDNA. Excludes Neandertal mtDNA contribution greater than 25% 30,000 years ago under constant population model. Smaller contributions not ruled out but no positive evidence found. Neandertal mtDNA diversity matches modern humans, lower than apes. Early modern humans double Upper Pleistocene mtDNA sampling. Constant population size model rejects 25%+ Neandertal admixture at 5% significance. Population expansion scenarios exclude even smaller contributions. Fifty early modern humans needed to exclude 10% Neandertal mtDNA input. No mtDNA gene flow detected from Neandertals to modern humans or vice versa. Neandertal primers amplify only from Neandertals, not modern humans. All Neandertals share distinct mtDNA substitutions absent in humans.